In the US, the DC volt is legally defined by the Josephson array — a super conducting quantum device with a highly repeatable output voltage. Banks of standard cells and temperature-stabilized zener diode references are used by the National Institute of Science and Technology (NIST) to calibrate DC meters for scientific and industrial customers. So how is the AC volt defined?
How many times each day do you pick up a probe to measure a DC voltage? The meter reads, say 4.65 volts, and we usually accept it without question. But just what is a volt and how is it maintained? Here's a fascinating look at the search for increasingly more accurate methods of building a “standard volt.”
The most powerful computer in the universe is actually the simplest. Explore the concept of Turing Machines and experiment with a simple Turing Machine simulator.
In the fast moving world of digital electronics, I find it incredible that the vacuum tube — a piece of early 20th century analog technology — has managed to survive. It should have bitten the dust long ago but that just did not happen. This back-to-the-future one-tube radio is made with readily available parts, operates on 12 volts, and offers amazing performance.
Perhaps one day soon we’ll have a battery that displays no “memory” effect; can be completely discharged or overcharged without harm; and require no complex computerized management system. Does such a battery sound like too much to hope for? Thomas Edison didn’t think so.
Who was Hugo Gernsback? The answer depends on whom you ask. “Gernsback published the first science fiction magazine!” a science fiction reader will declare. Ask an engineer and you might hear, “Gernsback ... wasn’t he involved in early experiments with television broadcasting?” Others will recall Gernsback’s radio magazines. A radio historian will tell you that Hugo Gernsback owned radio station WRNY, introduced the first home radio set (1905), and championed the cause of radio amateurs.
Most folks believe that first came the vacuum tube and right on its heels came its successor, the transistor — an historical fact, correct? Not really. Another competitive control technology developed by US and Nazi engineers came in between. It was the magnetic amplifier. Rugged, dependable, EMP-proof, and capable of handling greater electrical powers than either transistor or tube, the magnetic amplifier is a simple device that can be built by anyone.
